Air compressor apparatus



2 Sheet s-Sheet 2L March l, 1947. E." E. HEwTT ETM.

AIR Z'EMPRESSOR APPARATUS .Filed Aug. A g1, '1943 ATTORNEY March ll, 1947. l E. E. leu-:WITT ETAL; ZWJW AIR COMPRESSOR APPARATUS Filed Aug. 21', 1943 2 shams-sheet 2 *Fig 3 INVENTORE ELLIS EHEWWT' RANKINJ.BUSH BWIL UAM H GQLAES azz maze ATTORN EY Patented Mar. 11, 1947 UNITED- sTATEs PATENT OFFICE am COMPRESSOR arwimrrns Ellis E. Hewitt, Edgewood, Rankin J Bush, Jeannette, and William H. Glass, Wilkinsburg, Pa.,

assignors -to The Westinghouse Air Brake Comy pany. Wilmerding, P a., a corporation of Pennsylvania Application August 21, 1943,'Serial-No. 499,470

rlhis invention relates to air compressors, and more particularly to a single stage air compressor adapted to be substituted for that shown in Fig. 1. automotive vehicle. Trucks and other automotive vehicles, particularly those employed in military operations orl other work requiring the making of long trips far from any center of servicer and supply, may be.

economically equipped with light-duty compressors that can be operated at any time to afford av quick supply of compressed air for inflating tires or other equipment. Various types of'compressors for automotive service have heretofore been proposed, but many of these machines are considered unsuitable forv quantity production, or

impracticable under. the unfavorable' operatingr conditions sometimes encountered, by reason off constructions requiring expensive or scarce materials, or involving weak and unserviceable designs, or embodying excessively heavy and bulky assemblies.

adapted to be substituted for that shown in Fig. 1. f

According to the invention as illustrated in the drawings, the air compressor is of a single stage type, and is provided with a pair of oppositely disposed cylinders in which is vmounted a double pistonl unit that is operative through the medium of a crank shaft and belt-driven pulley. Referring to Fig. 3 of the drawings, the casing structure of the compressor consists of only two It is a principal object of our invention to proi vide an improved single stage vair compressor of `compact form-suitable for belt-drive connection with a vehicle engine, which is so constructed and arranged as to require a relatively low driving torque vfor fast operation to deliver a large volume I of air under high pressure, and which embodies a design facilitating its manufacture by mass production methods.

Another 'object of the invention is to provide improved compressor of the above type having a symmetrical, two-part casing structure that may be readily assembled or taken apart for repairs, and which constitutes a compact, properly balanced unit adapted to be mounted in any convenient position in association with` an automobile engine or the like.

A further object is to provide a compressor of the class described having an improved piston and valve structure, and other features of construction rendering the apparatus suitable for operation under dustry service conditions for long intervals, without requiring frequent inspection or repairs.

Still another object of the invention is to provide an air compressor exhibiting the above advantages and having `automatically controlled driving means adapted to prevent inadvertent voperation of the compressor at excessive speeds.

Other objects and advantages of the invention will appear in the following more detailed description, taken in connection with the accompanying drawings, in which Fig. -1 is a lon-gitudinal sectional view of an main parts, designated as a body section I0 and a complementary body section I I. 'These body sections are substantially alike in form, and are4 ,adapted to be bolted together for housing all of the operating elements of the compressor with the exception of the driving pulley assembly. The body section I0 has a cylinder portion I3 and a crank case portion III terminating in a flat sealing surface I5. The complementary body section II of the casing structure likewise includes al cylinder portion I1 and a crank case portion I8 having a sealing surface -I9 adapted to be held in abutting relation with thesealing surface I5, when the parts are assembled.

The two body sections I0 and I I are adapted to be held together by four bolts, two of which are identified in Fig, 3 by thc reference character 2U, that are inserted through suitable apertures in the casing sections adjacent the driving pulley assembly of the compressor. The other two bolts 2| are relatively short and are inserted through suitable openings in flanges 22 and 23 carried by the body sections I0 and I I, respectively, as shown in Figs. 3 and 4.

Also best illustrated in Figs. 3 and 4 of the H drawings are the mounting brackets for sup-l porting the compressor assembly. comprisingfour projecting lug portions 26 suitably apertured and 1 aligned in integral pairs -on the outer end of the cylinder portion I3, and four similar lug portions 21 integrally formed on the cylinder 110111101! l1 of the other body section. It will be'observed that the lug portions 26 and 21 are conveniently disposed for facilitating the mounting of the compressor in any of a number of different positions. As hereinafter more fully explained, the lug por- 32 in the opposite cylinder portion I1 of the other body section. The piston bores 3| and 32 both open into a centrally disposed crank case chamber 33 defined within the abutting portions I4 and I8 of the two body sections. This chamber communicates with an air intake opening 35 that is defined by the body sections I0 and I and that is adapted to be covered by a removable air filter unit 38, hereinafter described. The outer end of the cylinder portion |3 has a bossportion 31 fitted with a screw-threaded cap member 33, which, tof' gether with the portion, defines a small valve chamber 39 communicating with the piston bore 3|. A similar boss portion`40 is formed on the cylinder portion I1 and-contains a valve chamber ill, which is closed by a'cap member e2.

operatively mounted within this casing structure is a double piston or movable abutment cornprising a longitudinally disposed shank 43. having formed at one end a piston head 44 which is slidably fitted in the piston bore 3|, and at the opposite end a similar piston head 45 slidably mounted in the other piston bore 32. The piston head 4I is adapted to compress air in the bore 3 I, and for this purpose is provided with a flexible annular packing cup 43, which may be made of rubber or a similar material and is held on the piston head by means of a ring element 49 having screwthreaded connection with a central stud 50. The skirt of the packing cup 43 is adapted to engage and seal against the wall of the bore 3| during each compression stroke of 'the piston head 44, and is also adapted' to perform the function of an inlet valve during each suction stroke, by

\ controlling admission of ai-r to the piston borel through a plurality of lateral slots 5| formediin the peripheral portion of the piston head. X Back flow of air from the valve chamber 39 to the piston bore 3| is prevented by a discharge valve 53, which is disposed in valve chamber 39 and is normally maintained in -engagement with an annular seat rib 54 by a spring 55 supported on cap member 3k, l

The opposite piston head is likewise provided with lateral slots 58 and a Aflexible packing cup 60, that is held in place by an annular nut 6I secured to a stud 62 projecting from the piston head. Communication between the piston bore 32 and valveV chamber 4I is controlled by a valve element 64, which is normally held on a seat rib 05 by a spring 61.

It will be observed that both the valve chamber 4| and the valve chamber'39 are connected to a common dischargemanfold or conduit 66', which, as is best shown in Figs. 3 and 4, is disposed closely adjacent the casing structure of the compresser, with one end of the manifold secured to the boss portion 31 and the other end to the boss portion 40 by means of suitable pipe fitting assemblies. The central portion of the manifold 56 is preferably arranged substantially in the plane occupied by the air filter unit 36 and may be bent sufficiently to clear that element. At the end supported by the boss portion 31 of body section I0, the discharge manifold 66 is equipped with an extension 66a, to which a suitable pipe fitting or hose coupling may be attached. This arragement of the extension 66a adjacent the junction of the manifold 66 with the casing insures proper support for the necessary pipe coupling elements.

For reciprocating the movable abutment just described, there is provided a crank shaft 10, an intermediate portion of which is journaled in a sleeve member 1I having one end tightly ttcd and clamped between suitable eoncavities formed in the portions I4 and I3 of the respective body sections l0 and II. The sleeve member 1| is preferably equipped with anti-friction linings 12 made of a suitable bearing metal. and is securely held against slipping between the complementary body sections with the raid of a resilient packing ring 14 of rubber or the like, which also tends to absorb vibration and acts as a seal. The yend of the crank shaft 10 extending into the crank case chamberv 13 carries a counter-weight portion 16 and an oppositely disposed crank arm 11 which terminates in a crank pin 18. Journaled op the crank pin 10 is one end of a vconnecting rod 80. the opposite end of which is pivctally connected toa wrist pin 8|, which is mounted in bridging relation with. the portion of the shank 43 adjacent piston head 44 and a suitable bearing lug thereof ,l designated by the numeral 02.

The air compressor constructed in accordance with our invention is adapted to be lubricated by grease or a relatively heavy oil,'in order to reduce to a minimum any tendency of the compressor to provided with alongitudinally arranged lubricantv duct 85, which may be supplied with lubricant by way of a suitable pressure fitting 88 inserted in the outer end of the crank shaft. The duct l5 communicates through branches 31 with the crankshaft bearings. An auxiliary lubricant duct 88 also leads to duct 85 and .terminates at another pressure fitting 89 screwed into the body section I0. The end of the lubricant duct l5 within the crank pin v18 communicates by-way of a branch 90 with .the connecting rod bearing, and also with a lubricant duct 9| passing through the connecting rod to the bearing surrounding the'wrlst pin 3 I.

Mounted on the outer end of the crank shaft- 10 is a driving pulley assembly, indicated generally by the reference numeral |00, which comprises anannular pulley member` |0| having a V'shaped channel |02 adapted to receive a driving belt, not shown. A pair of ball bearing .assemblles |03 and |04 are provided to support the pulley member |0| in rotatable relation with the sleeve member 1I. y |00 also includes a coupler. disk |06 which is keyed or otherwise secured to the end of the shaft 10 for rotation therewith, and irs-held in place by means of a lock nut |01 screwed onto the end of the shaft. The coupler disk |06 has a plurality of. spaced apertures |08 formed therein at equal distances from the axis of the disk, and is The driving pulley assembly disk |06, and the inner race of the other bearing assembly |03 occupying a position close to extensions of the body sections and l0, as

shown in Fig. 1.

According to the invention, the plunger I is 'arranged for movement into and out of engagement with the coupler disk |06 for establishing and disestablishing the driving connection b`e tween the pulley member |0 and the crank shaft 10 of the compressor, the disconnecting or uncoupling operation being automatically accomplished upon operation of the apparatus at a predetermined speed. As shown in Fig. 1, the plunger ||0 is subject to the pressure of a coil spring |20,

which is interposed between the end Wall |2| of In actual practice, the air compressor constructed in accordance with our invention is preferably mounted on or in association with the engine of a truck or other automotive vehicle, with the driving pulley assembly |00 so located as to enable voperation thereof by the fan belt, or by an auxiliary belt driven by the engine. By reason of the compact, symmetrical form of the compressor assembly, and the plurality of conveniently located mounting lug portions 26. and 21 previously described, the compressor may readily be accommodated to any of a number of support- `ing lbrackets associated with the engine. Mountthe plunger and a 'pin |22 secured to the pulley member |0|. The pin extends througha longitudinally arranged slot |23 formed in the plunger. The spring is adapted` to urge the plunger I0 inwardly toward the body of the compressor and away from interlocking engagement with the cou,- pler disk |00. v

For maintaining the plunger ||0 in its engaged position, as shown in Fig. 1, there is provided an inertia responsive mechanism including a lever |25 carrying a locking bar |26, which is adapted for overlapping engagement with the plunger .l I0

`while the latter is interlocked with the coupler disk '|06. The lever |25 is further shown in Fig. 2 as comprising a weighted portion |21 extending beyond a curved portion to which the bar |26 is riveted, and a journal portion which is pivotally mounted on a pin |20 carried by the pulley member |01. An extension |30 of the lever |25 of a coil spring 83|, which is seated on a fiat portion of the hub |0|a ofthe pulley member. The spring |3| is arranged to bias the lever |25 in a clockwisedirection'with respect to the pin |25, as viewed in Fig. 2, so that the bar |26 is normally urged toward'the position in which it is illusing of the compressoris further facilitated by reason of the fact that the ystructure does not include the usual oil lled crankcase, the compressor being thus adapted to operate with equal efficiency in all positions.

In operationwhen the plunger Ill)` is positioned in engagement in one of the apertures |00 of the coupler disk |06, the pulley member |02 may be rotated by the vehicle engine to drive the crank shaft 10 at a speed corresponding with the speed of the engine. As it rotates the crankl shaft 10 acts through the medium of the con; necting rod60 to reciprocate the piston heads 04 and 45 within the respective cylinders. It should be understood that each of the piston heads 44 and 45 is operative, during its suction stroke, to draw air from the atmosphere into the piston bore by way` of the strainer unit 36, crank case chamber 33, and the slots in the piston head leading past the associated packing cup, and that the air compressed on the subsequent compression stroke of the piston head is discharged past the associated discharge valve into projects beyond the pin |29 to receive the end the manifold 66. The flow of atmospheric air past the respective packing cups 46 and 60 carries off some of the heat'developed therein dur- The air filter unit 36, which asalready stated covers the inlet opening 35 in the casing structure, comprises a substantially cylindrical body |36 which may be made of a plastic material, and

which is held in place by a pair of spring clips n |31 and |38. The spring clips are pivotally at- I tached to'suitable brackets riveted to the respective body sections of the casing structure at opposite sides of the opening 35, and are adapted to engage an annular flange provided4 on the body |36, as shown in the'drawing. A lateral opening |39 formed in the body |36 provides communication from the atmosphere through a chamber containing curled hair felt, or other'straining material |40\to the crank case chamber 33 of thecompressor.` The straining material |40 is contained between a pair of perforated plates |4| which aresecured to the body |36 by means of an axially disposed rivet M3, so that the entire body unit 3B may be removed for cleaning purposes, and later installed again without loss of any of .its elements.

ing operation of the piston head, while heat of compression is also dissipated by radiation from the surfaces of the exterior mounting lug portions -20 and 21 carried on the compressor cylinders The packing cups are thereby protected from the possibility of damage that might follow an excessive rise in temperature.

If the speed at which the driving pulley assembly |00 is rotated to operate the compressor exceeds a predetermined rate, so that the centrlfugal force acting on the weighted portion |21 of the lever |25 shown'in Fig. 2 becomes great `enough to move the lever in a counterclockwise direction about the pin |29, in opposition to the force of the spring |3| the bar |26 is then moved out of engagement with the plunger ||0. With the plunger ||0 thus released, the spring |20 acting thereon, shown in'Fig. 1, becomes effec- Ytive to force the plunger out of engagement with the coupler diskV |06 carried by the crankshaft of the compressor. The pulley member HJI is thereafter free to rotate at the speed determined by the driving engine speed, but operation of the compressor is discontinued.

It will be apparent that the driving pulley asjA sembly |00 thus embodies an elficient feature of construction automatically operating to prevent excessively rapid operation of the compressor assembly. When the compressor is mounted'on a motor driven vehicle, the inertia responsive un coupling mechanism also serves to prevent inadvertent operation of the compressor when the vehicle is driven over the road by an operator who has forgotten to render the compressor inoperative, after having used it in inflating tires or the like.

- A animer disk |06 secured to the compressor crank shaft 10, and 'means for connecting the coupler disk to the pulley member including a spring pressed plunger |52 carried by the pulley member. The

plunger |52 is slidably mounted in a bore formed in the pulley member |50 for operation into or out of engagement in one of the several apertures |08 formed in thecoupler disk. A coil spring |53 is interposed between the end wall of the plunger and a pin |50 fitted through a slot |55 in the plunger for urging the latter element toward its disengaged position. In this form of the apparatus, the plunger |52 is provided with a lateral opening |51 adapted to receive the end of an inertia responsive latch mem- 4 `ber |58, which is disposed in a radially arranged bore |59 in the pulley member. A coil spring |60 is interposed between a ring |6| secured to the pulley member |50 and a collar |52 formed on the latch member |50 for urging the member inwardly toward the plunger |52.

In principle, the operation of the pulley assembly shown in Fig. 5 is like that of the apparatus already described with reference to Fig. 1. So long as the compressor is driven at a safe speed, the spring |60 maintains the latch chamber |58 in engagement with the aperture |51 in plunger |52. The plunger thus is 'suillcient to lock the driving pulley member, |50 to the coupler disk |06 and crank shaft 10. Upon rotation of the pulley member |50 at a rate exceeding the predetermined speed, however, the latch member |58 moves outwardly under theforce of inertia and releases the spring pressed plunger |52, which is then withdrawn from the aperture |08 in the coupler disk..

It .will now be seen that the improved air compressor embodying the features of our invention, as hereinbefore described, incorporates maximum effectiveness of design and structural strength in a compact and durable unit that is markedly suitable for assemblyy by the application of modern mass production techniques. The two-part compressor casing, the symmetrical form of the completed uni-t, and lits carefully balanced operating elements, together with the protective features including the automatic coupler or unloading mechanism associated therewith, all contribute to attainment of the objects and advantages of the invention as initially presented.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An air compressor comprising a symmetrical 2. In an air compressor, in combination, a pair of separate hollow body sections each having a cylinder portion and an enlarged crank case por-` tion, said crank case portions having matching concavities and apertured corner bolting faces, a movable abutment having opposed piston heads constructed and arranged to fit into the respective cylinder portions of .said body sections, a crank shaft operatively connected to said movable abutment, a sleeve member arranged to serve as a journal for said .crank shaft and having one end adapted to be received into said concavities and clamped by said body sections against movement' in any direction whenl said body sections are assembled in end to end relationship with each other vabout said movable abutment and crank shaft, and a plurality of `bolts applicable to said bolting faces on the body sections for securing said assembled elements of the air comi pressor together. 1

3. In a compressor, in combination, a casing structure, fluid compressing means operatively mounted therein, a sleeve member rigidly supportedl in said casing structure and extending outwardly thereof, a' rotary shaft journaled in -said sleeve member and constructed and arcasing structure consisting only of two substanreciprocatively mounted in said cylinders, respectively, a sleeve member clamped between said sections against movement, crank shaft means mounted in said crank case chamber and jour- A naled in said sleeve member for operating said unitary piston means, and driving means supported on said sieeve member for operating said crank shaft means.

ranged to operate said fluid compressingl means within the casing structure, a pulley member rotatively mounted on said sleeve member, a couplerI disk secured to said rotary shaft adjacent said pulley member, locking means carried. by said pulley member for engagement with said coupler disk, and inertia responsive means operative to render said locking means ineective upon rotation of said pulley member at an excessive speed.

4. A single stage tire inflation compressor having a casing structure consisting of two like sections each having a cylinder portion, crank case portion and recessed bearing support portion,

said sections being adapted when joined to form an atmospherically open crank case and intake chamber intermediate oppositely disposed compression chambers, a double piston member extending through the crank case and intake chamber and having opposed slottedA heads mounted in the respective compression chambers,l self-lubricating flexible packing cups carried on said slotted heads and operable to admit air from said crank case and intake chamber by way of the slots in the respective heads to the compression chambers during suction strokes,a tubular sleeve member having a portion adapted to be clamped between the bearing support portions of said casing sections, a crank shaft journaled in said sleeve member and operatively con` nected to said piston member, rotary driving means adapted to be connected to said crank shaft and journaled on the outer end of said sleeve member, and bolts fitted exteriorly to said casing sections, said bolts serving as the sole securing means for holding said sections.and thereby all said other elements in assembled relation.

5. A single stage tire inflation compressor having a casing structure including a cylindrical bearing sleeve member, air compressing means operatively mounted in said casing structure. a rotary operating shaft journaled'in said. sleeve member for operating said air compressing means, a rotary driving element journaled exteriorly on said sleeve member, and means for detachably coupling'said driving element to said operating shaft comprising a coupler element secured to said operating shaft adjacent said animer driving element, a, manually operable pin carried by said driving element and movable into locking engagement with said coupler element, a spring serving to urge said pin out ,pf such engagement, and inertia responsive centrifuge means constructed and arranged to retain said pin in locking engagement with said element unless said compressor is driven in excess ofa preselected speed, in which event said pin must be manually reset when operation of the compressor is to be resumed.

6. An air compressor comprising a casing.

crank contained in said crank case chamber and operatively, connected to said unitary piston means for imparting reciprocatory motion thereto, an air inlet to said crank case chamber, and

-means carried by said air compressing heads op erative to admit air from said crank case chamber to said piston chambers for compression by said air compressing heads.

7. in air compressor comprising a casing structure comprising two substantially similar sections each having provided therein an air compressing Lpiston chamber and both sections being secured together in end to, end relationshipwith each other to axially align the air compressing piston chambers and to provide a central crank case chamber intermediate the axially aligned air compressing piston chambers, said crank case chamber being constantly devoid of liquid i0 lubricant, unitary piston means having air compressing heads facing in opposite directions from each other and reciprocatively mounted in said piston chambers, respectively. crank shaft means carried by the casing sections and comprising a crank contained in said crank case chamber and operatively connected to said unitary piston means for imparting reciprocatory motion thereto, Vflexible packing cups carried by the respective piston heads, an air inlet for admitting air t0 said crank case chamber, means for admitting air from said crank case chamber and Ipast said packing cups to said piston chambers "during suction strokes lof said piston heads, and

discharge valve means mounted in said casing sections in association with saidair compressing Number piston chambers.

ELLIS E. HIEWII'I'. RANKIN J. BUSH.

vWILLIAM H. GLASS.

' REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Dinesen June 14, 1927 McCune Jan. 25, 1938 Geiger July 11, 1933 Bornholdt Feb. 24, 1891 Miles 1 July 1'?, 1906 Pocock et al Apr. 13, 1909 Guthrie May 15, 1917 Wishart et al. Nov. 29, 1921 McCormack .L Jan. 5, 1932 Hall Oct, 18, 1932 Sions v Oct. 1'7, 1939 Lamberton Nov. 16, 1943 Lawhead 1..---.. Aug. 15, 1922 Aikman June 14, 1927 

